Dressing



Sept. 3, G A CROWE JR.` ET AL DRESSING Filed Feb. 8, 1966 Turi..

INVENTORS CX40( 645m A/E/P ATTORNE y United States Patent C 'I 3,399,672 DRESSING Jack H. Gardner, Highland Park, and George A. Crowe, Jr., Plainfield, NJ., assignors to Johnson & Johnson, a corporation of New Jersey Filed Feb. 8, 1956, Ser. No. 525,895 9 Claims. (Cl. 128--156) This invention relates to film faced dressings of the type having relatively low adherence to healing wounds and, more pa-rticularly, to dressings of this type having improved absorbency rates.

In order to reduce the adherence of absorbent dressings to wounds, it has been proposed to have on the wound contacting surface a thin film of either metallic or organic material. Openings a-re formed in the film so that the wound exudate can pass through the film to the absorbent substrate. Dressings of this type are described, for example in British Patent No. 439,085 to Gelinsky, United States Patent No. 2,877,765 to Bunyan, and United States Patent No. 2,923,298 to Dockstader.

The difficulty with even the most efficient dressings of this type has been that since the film material itself is not absorbent and is generally hydrophobic and, therefore, nonwetting, absorption of the wound exudate by the dressing does not take place until there is sufficient build-up of the wound fluids to cause lateral flow of the same to a point immediately under a perforation in the film where, when suflicient fluid has collected, it flows through the perforation to the absorbent substrate. This necessitates the placing of perfo-rations close together as well as necessitating the formation of perforations or other openings of appreciable size to assure a steady flow of the wound exudate into and through the perforations and to avoid fluid-up.

It has now been found that the absorption rate of film faced dressings of the type described above can be substantially improved with the -result that the wound surface is maintained in a drier state, by treating the wound contacting surface of the film with a surface active agent to increase the surface tension of the same. The surface active agent must be of a type that is non-irritating to healing wounds and should be relatively insoluble in wound exudate. When the films are so treated, the wound exudate wets the same and, as a result, moves rapidly laterally along the surface to adjacent perforations through which it is carried to the absorbent substrate and on into the main body of the dressing.

The above described surfactant treatment of the wound contacting surface of the film facing of the dressing should not be confused with the heretofore proposed impregnation of the absorbent substrate of dressings to improve the absorbency of the same. In the latter instance, the surfactant acts to emulsify the wound fluids after they have been absorbed and thus prevents the formation of a coagulum on or near the surface of the absorbent substrate but does not serve to expedite movement of wound exudate along the film su-rface to the openings in the film.

The inventive concept is more fully described by the following description and the accompanying drawings. In the drawings:

FIG. 1 is a plan view of a dressing of this invention illustrating the wound contacting film facing thereof;

FIG. 2 is a cross section of the dressing illustrated in FIG. 1, taken along line 2 2.

Referring now to the drawings, there is illustrated a dressing comprising an absorbent fibrous substrate 1, a thin relatively smooth moisture impervious hydrophobic organic film 2 covering one surface of the absorbent 1, and a backing sheet 3 covering the other surface. The

Patented Sept. 3, 1968 lCe organic film 2 defines a series of openings in the form of semicircular slits 4. The slits tend to bend away somewhat f-rom the absorbent 1, especially when the dressing is bent or deformed, to provide a path for the flow of wound fluids from the wound contacting surface of the dressing to the absorbent substrate. The exposed surface of the film facing 2 has been treated with a surfactant 5, as a result of which the exposed surface of the facing has a surface tension which is greate-r than that of blood and other wound exudates. Thus wound fluid, and most importantly wound fluid which initially contacts the film in areas 6 between the slits 4, wets the film and tends to spread out rapidly laterally toward the adjacent slits 4 where it is absorbed into the body of the dressing.

Wound fluids, in general, have a surface tension which approximates that of water, that is, about 72 dynes/cm. On the other hand, the surface tension of most organic films is below about 55 dynes/cm. and the surface tension of metallic films is even substantially lower than this. It is, therefore, necessary to treat the surface of the film with a surface active agent to increase the surface tension of the fil-m to `72 dynes/cm. or more.

A variety of hydrophilic and lipophilic surface active agents are available which are suitable for treating the surface of organic and metallic films to increase the surface tension thereof. These surfactants, which would be well known to those skilled in the art, include, for example, hydrophilic surfactants such as the monoand diglycerides, especially the palmitates, stearates, and oleates; the sorbitan fatty acid esters, especially the laurates, palmitates, stearates and oleates; and the polyoxyethylene sorbital esters. Suitable lipophilic surfactants include the polyoxyethylene acids; the polyoxyethylene alcohols, especially lauryl, cetyl, steryl, and olyl and tridectyl; and the polyoxyethylene sorbitan fatty acid esters. All of the above identified surface active agents are nontoxic and are essentially nonirritating to skin or body tissue.

Hydrophilic surface active agents, in general, may be used to provide a somewhat higher surface tension than Ithe lipophilic surface active agents. However, the hydrophilic agents are somewhat soluble in water and may tend to be dissolved by the initial surge of wound fluids and may, therefore, be wicked into the absorbent or into the wound, thus reducing the surface tension of the exposed surface of the lfacing to its normal level. While it might be expected that the wound fluids would tend to stick to surfaces treated with hydrophilic surfactants thereby reducing the nonwound adhering nature of the dressing, it has been surprisingly found that hydrophilic surfactants may be used without causing substantial sticking of wound fluids to the film. The lipophilic surface active agents, on the other hand, are relatively insoluble in wound fluids and have the additional advantage that surfaces treated with these agents are somewhat more slippery with respect to the wound fluids, thus allowing the fluids to spread more rapidly laterally along the surface of the film.

As mentioned above, either the lipophilic or hydrophilic surface active agents may be used to tre'at the films according to this invention. If only hydrophilic surface active agents are to be used, the members of the polyoxyethylene sorbitan fatty acid ester series, especially the polyoxyethylene sorbitan monolaurate, have been found to be particularly suitable. If only lipophilic surface active agents are to be -used to treat the film, the members of the sorbitan fatty acid ester series, especially sorbitan sesquioleate, have been found to be particularly suitable. However, it will usually be desirable to use a mixture of hydrophilic and lipophilic surfactants in order to take advantage of the various properties of the saine and provide a film surface which has a surface 3 tension which is substantially greater than that of wound exudate and which remains at this high level even after prolonged contact with `wound exudates and to provide a film surface which is relatively slippery with respect to the wound exudates. A particularly suitable mixture of lipophilic and hydrophilic surface active agents comprises from about 60% to about 70% of polyoxyethylene sorbitan monolaurate and from about 30% to Iabout 40% of sorbitan monolaurate.

It is preferable to treat the surface of the film directly with a surfactant and the particularly surface `active agents disclosed above would generally be used in this manner. However, the surface active agent may also be incorporated into the film itself, if the agent is of the type which will migrate to the surface of the film upon aging. Examples of this latter type of surface active agent are the anionic surfactants used in the emulsion polymerization of vinyl monomers. Thus, if a polyvinyl chloride film is used for the facing of the dressing, the surface active agents are conveniently incorporated therein.

Independent of whether the surface of the film .is treated directly with the surface active agent or whether a migratory agent is used, the surfactant should be present at the surface of the film in an lamount 'greater than about 0.1 mg. per square inch annd preferably greater than about 0.2 mg. per square inch. Although larger amounts of the surface active agent may be present Iwithout deleteriously affecting the functioning of the dressing, there would be little advantage to using amounts much greater than 0.3 mg. per square inch.

While this invention has `been described particularly with respect to using surface active agents to increase the surface tension of the film facing of a nonadherent dressing to a level greater than that of wound eXudate, namely about 72 dynes per centimeter, the inventive concept also contemplates the use of any physical or chemical treatment which, in effect, increases the surface tension of the exposed surface of the film to this level. As used in the specification and claims, surfactant treated includes any and all of such treatments.

What is claimed is:

1. A dressing comprising an absorbent substrate and a hydrophobic, surfactant treated film facing covering portions of 'at least one surface of said absorbent, said film having an outer surface and a surface contacting said absorbent, said film containing a series of openings through which wound exudate may pass to said absorbent substrate, the outer surface of said film having been treated directly with a surface active agent, the surface tension of the outer surface of said treated film facing being somewhat higher than the surface tension of wound exudate, by virtue of which wound fluids which contact the facing ywill wet the same and will tendy to spread laterally over said outer surface of said facing.

2. A dressing of claim 1 in which said surfactant is a lipophilic surfactant.

3. A dressing of claim 1 in which said surfactant comprises a mixture of a hydrophilic surfactant and a lipophilic surfactant.

4. A dressing of claim 1 in which said surfactant is present on the surface of said film facing in an.7 amount of greater than about 0.1 m'g./in.2.

5. A dressing of claim 1 in which said film is a nonmetallic, organic lm.

6. A dressing of claim 2 in which said lipophilic surfactant .is chosen from the group consisting of the polyoxyethylene acids and the polyoxyethylene sorbitan fatty acid esters.

7. A dressing of claim 3 in which said hydrophilic surfactant is chosen from the group consisting of monoand di-glycerides, the sorbitan fatty acid esters, and the polyoxyethylene sorbitan esters, and said lipophilic surfactant is chosen from the group consisting of the polyoxyethylene acids and the polyoxyethylene sorbitan fatty acid esters.

8. A dressing of claim 4 in which said surfactant is present in an amount of greater than about 0.2 nig/in?.

9. A dressing of claim 5 in which said nonmetallic organic film is polyethylene.

hydrophobie References Cited UNITED STATES PATENTS 2,796,362 6/1957 Wooding et al. 117-71 2,833,671 5/1958 Funk et al. 117-90 2,877,765 3/1959 Bunyan 128-156 ADELE M. EAGER, Primary Examiner. 

1. A DRESSING COMPRISING AN ABSORBENT SUBSTRATE AND A HYDROPHOBIC, SURFACTANT TREATED FILM FACING COVERING PORTIONS OF AT LEAST ONE SURFACE OF SAID ABSORBENT, SAID FILM HAVING AN OUTER SURFACE AND A SURFACE CONTACTING SAID ABSORBENT, SAID FILM CONTAINING A SERIES OF OPENINGS THROUGH WHICH WOULD EXUDATE MAY PASS TO SAID ABSORBENT SUBSTRATE, THE OUTER SURFACE OF SAID FILM HAVING BEEN TREATED DIRECTLY WITH A SURFACE ACTIVE AGENT, THE SURFACE TENSION OF THE OUTER SURFACE OF SAID TREATED FILM FACING BEING SOMEWHAT HIGHER THAN THE SURFACE TENSION OF WOUND EXUDATE, BY VIRTUE OF WHICH WOUND FLUIDS WHICH CONTACT THE FACING WILL WET THE SAME AND WILL TEND TO SPREAD LATERALLY OVER SAID SURFACE OF SAID FACING. 